1. Field of the Invention
The current invention relates to a power supply system for supplying power stably while achieving energy savings in, for example, offices and homes.
2. Description of the Related Art
Conventionally known environment-conscious power generation systems include solar energy power generation systems using solar cells and power generation systems using fuel cells.
The solar energy power generation systems are roughly classified into two, i.e., (i) an “independent system” and (ii) an “association system”. In the “independent system”, an electric energy generated by solar energy power generation is accumulated in a storage cell and then utilized. In the “association system”, a solar cell is connected to an electric line of a power company via an inverter. When the amount of power generated by the solar energy generation exceeds the power consumption in a house (for example, daytime on a clear day), the excess amount of the power is purchased by the power company; and when the amount of power generated by the solar energy generation does not reach the power consumption in a house (for example, a rainy day or nighttime), the necessary power is purchased from the power company.
One known example of power generation systems using fuel cells is a home-use co-generation system (see Nikkei Electronics, No. 763, pp. 55-62). The co-generation system described in this document realizes power generation using a fuel cell by providing a polymer-type fuel cell with fuel gas (for example, natural gas or LP gas). The electric energy thus generated is supplied to electric products in houses. The heat discharged from the fuel cell is used for hot water supply or room heating.
The solar cell power generation systems have a problem in terms of effective use of energy. In the “independent system”, the generated electric energy is accumulated in a storage cell, and thus an energy loss occurs. In the “association system” also, an energy loss occurs while the excess amount of the power which is sold to the power company is transferred thereto through an electric line.
The co-generation system using a fuel cell is expected to be common in homes and offices. However, it has not been considered how to build a new power supply system appropriate to a fuel cell, specifically, how to stably supply power while achieving energy savings.